The invention relates to handheld tools, and more specifically relates to handheld tools of the mechanically operable type. In its most immediate sense, the invention relates to ophthalmic surgical instruments of the Sutherland type.
Eye surgery requires the use of forceps, scissors etc. within the eye. Typically, a surgeon will make an incision in the eye and will then introduce a surgical instrument, e.g. a scissors, in the incision. The surgeon will then operate the scissors by actuating the tool.
A Sutherland-type instrument has a pen-type handle and uses a lever as an actuator. A variety of mechanically operable spring-loaded tools, e.g. scissors, forceps, knives etc. can be threaded onto the front tip of the handle immediately adjacent the lever. A surgeon operates the tool (i.e. opens and closes the forceps or scissors) by depressing the lever using his thumb or index finger. Such depression operates the tool against the pressure of its internal spring. After operating the tool, the surgeon releases the lever arm, causing the tool to return to its original state.
This type of surgical instrument has disadvantages. One such disadvantage is that keeping the instrument in the operated state (e.g. keeping a forceps in the closed position) while rotating the tool 180.degree. often forces the surgeon to assume an awkward posture and/or to use two hands when only one hand is conveniently free. Another disadvantage is that the instrument cannot conveniently be operated in all rotational positions, i.e. the tool cannot easily be operated unless the lever arm is e.g. adjacent the surgeon's index finger.
It would therefore be advantageous to provide a Sutherland-type instrument which could be easily and conveniently rotated about its axis even when in the operated state.
It would additionally be advantageous to provide a Sutherland-type instrument which could easily be operated in all rotational positions.
It would further be advantageous to provide a Sutherland-type instrument which could be used to operate tools designed to fit with existing Sutherland-type instruments, but which additionally would be suitable for operation in all rotational positions and which could be easily and conveniently rotated about its axis even when in the operated state.
In accordance with the invention as implemented in a pen-type tool, the actuator of a pen-type instrument is located at the end of an elongated handle. The actuator has an actuation surface which extends completely around the axis of the handle. The actuator is operated by applying pressure anywhere on this actuation surface. Because the actuation surface can be actuated at any point, there is no need to position an actuator lever adjacent the surgeon's index finger or thumb, and there is no difficulty in rotating the instrument while the actuator is operated.
In accordance with an alternate embodiment of the invention, the actuator has a mechanical advantage which is greater than unity, i.e. a small movement of the actuator causes a larger movement of the tool. This amplifies a surgeon's relatively small squeezing or pressing motion to a relatively large motion of the threaded-on tool.